There are methods and apparatus for manufacturing of three dimensional objects (for example U.S. Pat. No. 7,168,935) according to which three dimensional objects are formed by means of layered deposition of feedstock material on substrate when feedstock material is fed to melting zone moving relative to the substrate, is melt there by energy beam, for example by electron beam, and then solidifies when it is leaving heating zone resulting in formation of solid deposited layer of material. These methods and apparatus have such common character as application of thermionic axial electron beam guns of welding type as energy source for forming of molten pool on the substrate and melting of feedstock material. Such type of guns has appropriate current-voltage characteristics, first of all rather high accelerating voltage (60 kV and more), and they require creation of suitable operating conditions in operating chamber, first of all high vacuum (as a rule 10<″2>Pa and higher). Also electron beam in such methods and apparatus drop on the substrate perpendicular to its surface, and feedstock material, as a rule it is wire, is fed to melting zone from one side under some acute angle.
These characters cause some technological and economy problems among which the following problems must be underlined:                the requirement to create high vacuum in operating chamber causes essential increase of equipment cost because of usage of expensive high vacuum pumps and reduction of equipment efficiency because of increase of time which is necessary for evacuation of operating chamber before each production cycle;        relatively high accelerating voltage which is necessary for operation of electron beam gun of welding type causes generating of X-rays inside operating chamber, and protection of operating staff from radiation influence requires usage of much more thick operating chamber walls resulting in increase of weight of complete manufacturing system;        electron beam guns of welding type must be equipped by individual high vacuum pump for reliable protection of cathode during technological process which increases cost of equipment and makes complete system more large, heavy and complicated one;        cathodes of electron beam guns of welding type are made from rather expensive materials, nevertheless time of their permanent operation is rather limited;        usage of powder as feedstock material for deposition is very complicated because of technological reasons;        control difficulties in providing of feeding of feedstock material in accurate coordination with supply of electron beam to the same point on the substrate-melting zone, particularly taking into account permanent movement of this zone relative to the substrate especially in case when such relative movement is provided by movement both of electron beam gun and feed means in parallel;        shadow zone is formed on the substrate under the wire because feeding of feedstock wire to melting zone is executed from one side under the acute angle, this fact can cause creation of porosity or cavities in deposited layer because of deposition of molten feedstock material on the solid non-melted substrate, rather complicated irregular thermal fields are generated around melting zone because of the same reason resulting in much more complicated control of deposited material structure which is provided by specified solidification rate in each point, in addition one-sided heating of the wire, from the top, can cause bending of wire because of temperature gradients resulting in difficulties in accurate and stable feeding of feedstock wire directly to melting zone.        
The most similar technical solution to the present invention is U.S. Pat. No. 7,073,561 “Solid Freeform Fabrication System and Method”.
There is an existing method of solid freeform fabrication which is realized in vacuum through layered deposition of feedstock material on a mold structure, comprising directing an energy beam and feeding feedstock to a feed point (melting zone) adjacent to the mold structure (substrate), thereby forming a molten puddle, moving the feed point relative to the mold structure, thereby advancing the molten puddle of presently fed feedstock and rapidly solidifying previously fed feedstock, and sequentially advancing the feed point within a predetermined geometric volume containing at least a portion of the mold structure, thereby sequentially fusing the feedstock, by action of the advancing molten puddle, into a near net shape work piece built-up upon the mold structure.
Above said mold is fabricated from a material selected from one of: a composite matrix, a metal having a melting point substantially higher than the melting point of the feedstock, boron nitride, an inorganic compound, and graphite.
The said method further comprising the step of separating the mold from the work piece, disintegrating or dissolving the mold.
The energy beam in said method is selected from one of: an electron beam, an ion beam, a plasma beam, a flame spray, a gas tungsten beam, a metal arc, a gas metal arc, a microwave beam, a radio frequency beam, tungsten-inert gas beam, a metal-inert gas beam, and a laser beam.
A solid freeform fabrication system which realizes said existing method comprises a mold structure (substrate), a feed means operable to feed feedstock material to a feed point (melting zone) adjacent to the mold, an energy beam producing means operable to direct an energy beam to said feed point, thereby forming a molten puddle of feedstock material, a movement means coupled to said mold structure and operable to move said feed point relative to the mold, a controller coupled to control movement of said movement means to advance said molten puddle of presently fed feedstock and rapidly solidify previously fed feedstock, and to sequentially advance said feed point within a predetermined geometric volume containing at least a portion of the mold, thereby sequentially fusing the feedstock, by action of said advancing molten puddle, into the near net shape work piece built-up upon the mold support. There are following main disadvantages of above said method and system in embodiment with usage of electron beam as energy beam:                application of electron beam gun of welding type as energy source requires special additional conditions in operating chamber to provide normal operation of the gun, such as creation of high vacuum not less than 10<″>Pa and usage of individual high vacuum pump for cathode protection during the process, in addition walls of operating chamber must be thick enough to protect operating staff from X-rays generated because of high accelerating voltage, all these requirements result in more large, heavy, complicated and expensive equipment;        in case of usage of powder as feedstock material each granule of powder is getting negative charge under influence of electron beam during the process and granules can fly away from melting zone out of control due to electrostatic repulsion when negative charge accumulation is too high, resulting in uncontrollable deposition of powder causing worse quality of produced work piece and reduced efficiency of powder deposition process (increase of powder loss);        feeding of feedstock wire to melting zone from one side which is applied in said method causes generation of complicated asymmetrical thermal fields around melting zone because of unavoidable creation of shadow zone on the substrate under the wire which can result in creation of porosity or cavities in deposited layer and forming of non-uniform metal structure of produced work piece. In addition one-side heating of the wire, from the top, can cause internal thermal stresses resulting in bending of wire which cause difficulties in accurate and stable feeding of feedstock wire directly to melting zone which also results in violation of stable deposition and solidification conditions. These factors cause difficulties in providing of uniform structure and required quality of solid freeform work pieces fabricated by above said method.        